JP2023006657A - Mechanical quantity measuring device - Google Patents

Abstract

To improve the performance of a mechanical quantity measuring device.SOLUTION: A mechanical quantity measuring device 1 includes a semiconductor chip 2 on which a strain sensing circuit is formed, and an insulating base plate 3 on which the semiconductor chip 2 is mounted. The semiconductor chip 2 is bonded to the base plate 3 via a bonding material 5, and the bonding material 5 is preferably made of solder or metal nanoparticles. The mechanical quantity measuring device 1 is attached to an object 7 to be measured using a conductive bonding material 8. The strain generated in the object to be measured 7 is transmitted to the semiconductor chip 2 via the bonding material 8, the base plate 3, and the bonding material 5.SELECTED DRAWING: Figure 3

Description

There is an application for exception to loss of novelty

The present invention relates to a mechanical quantity measuring device.

Japanese Patent Laying-Open No. 2009-264976 (Patent Document 1) describes a technique related to a semiconductor strain sensor, and discloses a semiconductor strain sensor having a strain sensor chip mounted on a base plate.

Japanese Patent Laying-Open No. 2012-47608 (Patent Document 2) describes a technique related to a mechanical quantity measuring device using a bridge circuit.

JP 2009-264976 A Japanese Unexamined Patent Application Publication No. 2012-47608

A.H.Chokshi,A.Rosen,J.Karch and H.Gleiter;Scripta METALLUGICA:Vol23,1989,pp.1679-1684

Mounting the strain sensor chip on the base plate makes the semiconductor strain sensor easier to handle. However, in the case of a semiconductor strain sensor in which a strain sensor chip is mounted on a base plate made of metal, there are restrictions on how the semiconductor strain sensor can be used. performance may be degraded.

For example, if a semiconductor strain sensor with a strain sensor chip mounted on a metal base plate is attached to a metal object to be measured, the object to be measured and the base plate will be electrically connected, resulting in an electrical connection between the semiconductor strain sensor and the measurement. A current may flow between the object and the semiconductor strain sensor, and there is a concern that the semiconductor strain sensor may be affected by electrical noise from the object to be measured. On the other hand, in order to prevent conduction between the semiconductor strain sensor and the object to be measured, a semiconductor strain sensor with a strain sensor chip mounted on a base plate made of metal is attached to the object to be measured using an insulating adhesive. In this case, the performance of the semiconductor strain sensor may be deteriorated compared to the case where a conductive bonding material such as solder is used.

Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

According to one embodiment, a mechanical quantity measuring device includes a strain detector and an insulating structure on which the strain detector is mounted.

According to one embodiment, the usability of the mechanical quantity measuring device is improved. Also, the performance of the mechanical quantity measuring device can be improved.

1 is a plan view showing a mechanical quantity measuring device according to Embodiment 1; FIG. 1 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 1; FIG. FIG. 3 is a cross-sectional view schematically showing a state in which the mechanical quantity measuring device of FIGS. 1 and 2 is attached to an object to be measured; FIG. 3 is an explanatory view showing a planar configuration of a semiconductor chip used in the mechanical quantity measuring device of FIGS. 1 and 2; FIG. FIG. 4 is a cross-sectional view schematically showing a state in which the scholastic quantity measuring device of the study example is attached to an object to be measured; It is explanatory drawing which shows the result of having analyzed stress distribution. FIG. 10 is a plan view showing a mechanical quantity measuring device according to Embodiment 2; FIG. 5 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 2; It is the graph which showed an example of the result of having analyzed the strain transmissibility. FIG. 11 is a plan view showing a mechanical quantity measuring device according to Embodiment 3; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 3; FIG. 11 is a plan view showing a mechanical quantity measuring device according to Embodiment 4; FIG. 11 is a plan perspective view showing a mechanical quantity measuring device according to Embodiment 4; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 3; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 3; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 3; FIG. 11 is a plan perspective view showing a mechanical quantity measuring device according to Embodiment 5; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 5; FIG. 11 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 5; FIG. 20 is a plan view showing a mechanical quantity measuring device according to Embodiment 6; FIG. 12 is a cross-sectional view showing a mechanical quantity measuring device according to Embodiment 6; FIG. 11 is a plan view showing the mechanical quantity measuring device of Embodiment 6 before attaching a flexible substrate. FIG. 11 is a cross-sectional view showing the mechanical quantity measuring device of Embodiment 6 before attaching a flexible substrate.

Hereinafter, embodiments will be described in detail based on the drawings. In addition, in all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted. Also, in the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

In addition, in the drawings used in the embodiments, hatching may be omitted even in cross-sectional views in order to make the drawings easier to see. Also, even a plan view may be hatched to make the drawing easier to see.

(Embodiment 1)
<Regarding the configuration of the mechanical quantity measuring device>
A mechanical quantity measuring device 1 according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a plan view (top view) showing a mechanical quantity measuring device 1 according to the present embodiment, and FIG. 2 is a sectional view showing the mechanical quantity measuring device 1 according to the present embodiment. FIG. 1 shows a plan view of the upper side of the mechanical quantity measuring device 1, and a cross-sectional view taken along line A1-A1 in FIG. 1 substantially corresponds to FIG. Note that the X direction and the Y direction shown in FIG. 1 and subsequent figures are directions orthogonal to each other. Also, the X direction and the Y direction are directions substantially parallel to the upper surface of the base plate 3 and, accordingly, directions substantially parallel to the main surface of the semiconductor chip 2 .

As shown in FIGS. 1 and 2, a mechanical quantity measuring device 1 according to the present embodiment includes a semiconductor chip (strain sensor chip) 2 as a strain detector, and a structure in which the semiconductor chip 2 is mounted (supported and fixed). and a base plate (structure) 3 as a body. A semiconductor chip 2 is mounted on a base plate 3 with a bonding material 5 interposed therebetween.

The semiconductor chip 2 is a semiconductor chip in which a strain detection circuit (strain detection circuit, strain sensor circuit) is formed, that is, a strain sensor chip. Since the semiconductor chip 2 has a function of detecting strain (distortion), it can be regarded as a strain detector. The base plate 3 is an insulating structure on which the semiconductor chip 2 is mounted.

Specifically, the base plate 3 is a base plate (substrate) made of an insulating material, and a conductor pattern (conductor layer, wiring layer) 4 is formed on the base plate 3 as necessary. The conductor pattern 4 can also be regarded as part of the component of the base plate 3 . That is, the base plate 3 is mainly made of an insulating material, but can also include the conductor pattern 4 .

1 and 2, conductor patterns 4a and 4b are formed on the upper surface of the base plate 3 as the conductor pattern 4. In FIG. Among them, the conductor pattern 4a is formed in a region on the upper surface of the base plate 3 where the semiconductor chip 2 is mounted. Also, the conductor pattern 4b is formed around the area on the upper surface of the base plate 3 where the semiconductor chip 2 is mounted. The base plate 3 preferably consists of ceramic (ceramic material). Therefore, the base plate 3 preferably consists of a ceramic substrate. The conductor pattern 4 is preferably made of a metal material, such as an alloy film of molybdenum (Mo) and tungsten (W). The upper surface of the base plate 3 corresponds to the main surface on which the semiconductor chip 2 is mounted, and the lower surface of the base plate 3 corresponds to the main surface opposite to the upper surface.

In a plan view, the semiconductor chip 2 has a planar shape point-symmetrical with respect to the center of the semiconductor chip 2, and the planar shape of the semiconductor chip 2 is preferably square (substantially square). In a plan view, the base plate 3 has a planar shape that is point-symmetrical with respect to the center of the base plate 3, and the planar shape of the base plate 3 is preferably square. In the case of FIG. 1, each of the semiconductor chip 2 and the base plate 3 has a square shape having sides parallel to the X direction and sides parallel to the Y direction.

The semiconductor chip 2 is preferably mounted in the center of the upper surface of the base plate 3, and the semiconductor chip 2 is arranged so that the center of the semiconductor chip 2 substantially coincides with the center of the base plate 3 in plan view. is more preferable. Further, when the semiconductor chip 2 and the base plate 3 are square, it is more preferable if the semiconductor chip 2 is arranged so that the four sides of the semiconductor chip 2 are parallel to the four sides of the base plate 3, respectively. shows this case. As another form, the semiconductor chip 2 may be arranged such that each side of the semiconductor chip 2 is inclined at 45° with respect to each side of the base plate 3 . Here, the planar view corresponds to the case of viewing from a plane substantially parallel to the main surface of the semiconductor chip 2 or the upper surface of the base plate 3 .

The semiconductor chip 2 is bonded and fixed onto the conductor pattern 4 a on the upper surface of the base plate 3 via a bonding material (bonding layer) 5 . That is, the bonding material 5 is interposed between the semiconductor chip 2 and the conductor pattern 4a. As the bonding material 5, an insulating adhesive can be used, but a conductive bonding material is more preferable, and solder or metal nanoparticles can be preferably used. Here, typically, a metal material composed of metal particles having an average particle size of 1 to several hundred nm is called metal nanoparticles. When metal nanoparticles are used as the bonding material 5, for example, copper nanoparticles can be suitably used.

The conductor pattern 4 a is provided to facilitate bonding of the semiconductor chip 2 to the base plate 3 with the bonding material 5 . If the semiconductor chip 2 can be directly bonded to the upper surface of the base plate 3 with the bonding material 5 without the conductor pattern 4a, the conductor pattern 4a need not be formed on the upper surface of the base plate 3. FIG. However, when a conductive bonding material is used as the bonding material 5 instead of an insulating bonding material, the semiconductor chip 2 can be bonded to the base plate 3 via the conductive bonding material 5 without the conductor pattern 4a. hard to do. Therefore, in this embodiment, the conductor pattern 4a is formed on the upper surface of the base plate 3, and the semiconductor chip 2 is mounted on the conductor pattern 4a with the conductive bonding material 5 interposed therebetween. As a result, the semiconductor chip 2 can be firmly bonded to the conductor pattern 4a via the conductive bonding material 5, and the semiconductor chip 2 can be mounted on the base plate 3 and fixed.

The conductor patterns 4 b are electrodes (terminals) for electrically connecting to the electrodes 2 a of the semiconductor chip 2 , and are formed in plurality on the upper surface of the base plate 3 . Below, the conductor pattern 4b may be called the electrode 4b. The semiconductor chip 2 has a plurality of electrodes (pad electrodes) 2 a , and the plurality of electrodes 2 a are formed on the main surface (top surface) of the semiconductor chip 2 . A plurality of electrodes 2 a of the semiconductor chip 2 and a plurality of electrodes 4 b formed on the upper surface of the base plate 3 are electrically connected via a plurality of conductive wires (bonding wires) 6 . The wire 6 consists of a fine metal wire. One end of wire 6 is connected to electrode 2 a of semiconductor chip 2 , and the other end of wire 6 is connected to electrode 4 b formed on the upper surface of base plate 3 .

In this embodiment, the plurality of electrodes 2a of the semiconductor chip 2 and the plurality of electrodes 4b formed on the upper surface of the base plate 3 are electrically connected via the plurality of wires 6. As another form, the electrode 4b may not be formed on the upper surface of the base plate 3. FIG. In that case, a flexible substrate is connected to the base plate 3, and a plurality of electrodes of the flexible substrate and a plurality of electrodes 2a of the semiconductor chip 2 are electrically connected via a plurality of wires.

FIG. 3 is a cross-sectional view schematically showing a state in which the mechanical quantity measuring device 1 is attached (attached) to the measurement object 7. As shown in FIG.

As shown in FIG. 3 , when attaching (sticking) the mechanical quantity measuring device 1 to the measuring object 7 , the lower surface of the base plate 3 of the mechanical quantity measuring device 1 is attached to the measuring object 7 via the bonding material 8 . Joined and fixed. Although an insulating adhesive may be used as the bonding material 8, a conductive bonding material is more preferable, and solder or the like can be suitably used. Moreover, the measurement object 7 may have conductivity, and is made of, for example, a metal material.

Since the base plate 3 is an insulating base plate, a conductive bonding material (preferably solder) is used as the bonding material 8 when the measurement object 7 is made of a conductive material (preferably a metal material). Also, it is possible to avoid electrical connection between the measurement object 7 and the base plate 3 , thus avoiding electrical connection between the measurement object 7 and the semiconductor chip 2 .

In order to facilitate bonding between the base plate 3 and the measurement object 7 with the bonding material 8, a conductor pattern (not shown) is also formed on the lower surface of the base plate 3. It is also possible to bond the conductor pattern and the measurement object 7 via the bonding material 8 . In that case, the conductor pattern on the lower surface of the base plate 3 is preferably not electrically connected to the conductor patterns 4 a and 4 b on the upper surface of the base plate 3 and the semiconductor chip 2 .

By attaching (sticking) the mechanical quantity measuring device 1 to the measuring object 7 , the strain generated in the measuring object 7 can be detected by the mechanical quantity measuring device 1 . That is, the strain generated in the object to be measured 7 is transmitted to the base plate 3 via the bonding material 8 and further transmitted from the base plate 3 to the semiconductor chip 2 via the bonding material 5 . The strain transmitted from the object to be measured 7 to the semiconductor chip 2 via the bonding material 8 , the base plate 3 and the bonding material 5 is detected by a strain detection circuit formed in the semiconductor chip 2 . Therefore, the bonding material 5 not only has a role of fixing the semiconductor chip 2 to the base plate 3 but also has a role of transmitting strain from the base plate 3 to the semiconductor chip 2 .

Here, the case where the mechanical quantity measuring device 1 of the present embodiment is attached to the measuring object 7 is illustrated and described, but the mechanical quantity measuring devices 1a to 1e of Embodiments 2 to 6 described later are attached to the measuring object 7. The same is true for mounting.

Next, an example of the manufacturing process of the mechanical quantity measuring device 1 will be described.

To manufacture the mechanical quantity measuring device 1, first, the semiconductor chip 2 and the base plate 3 are prepared. Then, the semiconductor chip 2 is mounted on the base plate 3 via the bonding material 5 and bonded. Then, a wire bonding process is performed to electrically connect the plurality of electrodes 2a of the semiconductor chip 2 and the plurality of electrodes 4b on the upper surface of the base plate 3 through the plurality of wires 6, respectively. After that, a sealing resin (not shown) for sealing the semiconductor chip 2 may be formed.

<About semiconductor chips>
Next, a configuration example of the semiconductor chip 2 will be described with reference to FIG. FIG. 4 is an explanatory diagram showing a planar configuration of the semiconductor chip 2. As shown in FIG.

The semiconductor chip 2 is a semiconductor chip in which a strain sensing circuit is formed, that is, a strain sensor chip. A semiconductor substrate 11 forming the semiconductor chip 2 is made of, for example, silicon (specifically, a single crystal silicon substrate). The semiconductor substrate 11 has a planar shape point-symmetrical with respect to the center of the semiconductor chip 2, preferably a square planar shape.

As shown in FIG. 4, a semiconductor substrate 11 forming a semiconductor chip 2 is formed with four diffusion resistance regions 12a, 12b, 12c, and 12d arranged point-symmetrically with respect to the center of the semiconductor chip 2. As shown in FIG. there is These four diffusion resistance regions 12a, 12b, 12c, and 12d function as piezoresistive elements that capture strain as changes in electrical resistance. For example, the diffused resistance regions 12a and 12c function as piezoresistive elements that detect strain in the Y direction as changes in electrical resistance, and the diffused resistance regions 12b and 12d function as electrical strain in the X direction. It functions as a piezoresistive element that captures changes in resistance. Therefore, these four diffused resistance regions 12a, 12b, 12c and 12d form a strain sensing circuit.

In the strain sensing circuit formed on the semiconductor chip 2, the four diffusion resistance regions 12a, 12b, 12c and 12d constitute a bridge circuit, and the electric resistance in the four diffusion resistance regions 12a, 12b, 12c and 12d is Based on the change, a signal corresponding to the difference between the strain occurring in the X direction and the strain occurring in the Y direction is output. For example, the strain detection circuit formed in the semiconductor chip 2 is configured to output a change in electrical resistance corresponding to the difference between the strain occurring in the X direction and the strain occurring in the Y direction as a voltage value. Thus, according to the strain detection circuit that outputs a signal corresponding to the difference between the strain that occurs in the X direction and the strain that occurs in the Y direction, the output signal (output voltage) from the strain detection circuit increases. The advantage of being able to improve the detection sensitivity of is obtained.

It should be noted that the number of diffused resistance regions is not limited to four if the structure measures the difference between the strain occurring in the X direction and the strain occurring in the Y direction in terms of circuit configuration. For example, the number is not limited to four as long as they are arranged in parallel, and the number may be four or more. That is, the number of diffused resistance regions is not limited to four as long as the circuit is equivalent to that of FIG.

<Main features and effects>
One of the main features of this embodiment is that a semiconductor chip 2 (strain sensor chip) having a strain sensing circuit formed thereon is mounted (mounted) on an insulating base plate 3 . By mounting the semiconductor chip 2 on the base plate 3, the mechanical quantity measuring device 1 becomes easy to handle. For example, by bonding the base plate 3 of the mechanical quantity measuring device 1 to the measuring object 7 as shown in FIG.

FIG. 5 is a cross-sectional view schematically showing a state in which the mechanical quantity measuring device 101 of the study example studied by the present inventor is attached to the measurement object 107, and corresponds to FIG. A mechanical quantity measuring device 101 of the study example shown in FIG. 5 has a conductive base plate 103 made of a metal material, and a semiconductor chip 102 mounted on the base plate 103 via a bonding material 105. . The semiconductor chip 102 corresponds to the semiconductor chip 102 of this embodiment, and is a semiconductor chip (strain sensor chip) in which a strain sensing circuit is formed. As shown in FIG. 5, when the mechanical quantity measuring device 101 of the study example is attached to the measuring object 107, the lower surface of the base plate 103 of the mechanical quantity measuring device 101 is joined to the measuring object 107 via the joining material 108. fixed.

In the mechanical quantity measuring device 101 of the study example, the base plate 103 is a conductive base plate. If the base plate 103 is a conductive base plate, there is a possibility that problems may occur depending on the usage pattern of the mechanical quantity measuring device 101 . There is a possibility that the usability of the measuring device 101 becomes worse and the performance of the mechanical quantity measuring device 101 deteriorates.

For example, when the object 107 to be measured is made of a metal material (conductive material), the electrical connection between the base plate 103 and the object 107 to be measured causes electrical contact between the mechanical quantity measuring device 101 and the object 107 to be measured. There is a risk that a current will flow, and there is concern that the mechanical quantity measuring device 101 will be affected by electrical noise from the measurement object 107 . In addition, the above-mentioned Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-264976) states that the base plate on which the strain sensor chip is mounted is preferably made of the same material as the object to be measured, or a material whose coefficient of thermal expansion substantially matches. Accordingly, if the object to be measured is made of a metal material, the base plate on which the strain sensor chip is mounted is also made of a metal material. When both the base plate 103 on which the strain sensor chip (semiconductor chip 102) is mounted and the object 107 to be measured are made of a metal material, the base plate 103 and the object 107 to be measured are electrically connected as described above. When stored, a current may flow between the mechanical quantity measuring device 101 and the object 107 to be measured, and there is concern that the mechanical quantity measuring device 101 may be affected by electrical noise from the object 107 to be measured. . This degrades the performance of the mechanical quantity measuring device 101 .

Therefore, it is necessary to use an insulating adhesive as the bonding material 108 for bonding the base plate 103 made of a metal material to the measurement object 107 made of a metal material. As a result, it is possible to prevent the base plate 103 made of the metal material and the measurement object 107 made of the metal material from being electrically connected. It is possible to suppress or prevent the mechanical quantity measuring device 101 from being affected by electrical noise from the object 107 to be measured.

However, as the bonding material 108 for bonding the mechanical quantity measuring device 101 to the object 107 to be measured, an insulating adhesive is disadvantageous compared to a conductive bonding material such as solder. That is, when an insulating adhesive is used as the bonding material 108, the strain that can be measured by the mechanical quantity measuring device 101 is caused by the bonding strength, yield stress, fatigue strength, and stress relaxation characteristics of the insulating adhesive. There is concern that the range will be limited. In addition, there is a concern that the sensitivity of the mechanical quantity measuring device 101 may be lowered due to the elastic modulus of the insulating adhesive and the softening accompanying the temperature rise. In addition, there is a concern that the long-term reliability of the mechanical quantity measuring device 101 may deteriorate due to the fatigue strength, stress relaxation characteristics, and environmental resistance of the insulating adhesive. Since these concerns lead to deterioration in the performance of the mechanical quantity measuring device 101, it is desirable to eliminate or improve them. In order to eliminate or improve these concerns, it is effective to use a conductive bonding material such as solder as the bonding material 108 instead of an insulating adhesive. In the case of using an adhesive bonding material, there is a concern that there will be a problem due to conduction between the base plate 103 and the measurement object 107 as described above.

Therefore, in the present embodiment, a semiconductor chip 2 (strain sensor chip) having a strain sensing circuit formed thereon is mounted on a base plate 3 which is an insulating structure. Therefore, even if the measurement object 7 to which the mechanical quantity measuring device 1 is attached is made of a conductive material such as a metal material, the base plate 3 of the mechanical quantity measuring device 1 is not a metal body but an insulating material. It consists of a base plate. In this embodiment, the semiconductor chip 2 is mounted on the insulating base plate 3 instead of the metal base plate. It is possible to prevent current from flowing between the semiconductor chip 2 and the measurement object 7, and the semiconductor chip 2 of the mechanical quantity measuring device 1 is suppressed from being affected by electrical noise from the measurement object 7. or can be prevented. Thereby, the performance of the mechanical quantity measuring device 1 can be improved.

In addition, in the present embodiment, the insulating base plate 3 can prevent conduction between the semiconductor chip 2 and the object 7 to be measured. ), as the bonding material 8 for bonding the base plate 3 and the measurement object 7, an insulating adhesive can be used, or a conductive bonding material such as solder can be used. That is, when the measurement object 7 is made of a metal material, even if a conductive bonding material such as solder is used as the bonding material 8 for bonding the base plate 3 and the measurement object 7, the mechanical quantity measuring device 1 The semiconductor chip 2 of the mechanical quantity measuring device 1 can be prevented from being affected by electrical noise from the object 7 to be measured. can be suppressed or prevented. A conductive bonding material such as solder can be used as the bonding material 8 for bonding the base plate 3 and the object to be measured 7, thereby eliminating the above-mentioned concerns when the adhesive is limited to an insulating adhesive. can be improved. For example, the strain range measurable by the mechanical quantity measuring device 1 can be expanded, and the sensitivity of the mechanical quantity measuring device 1 can be improved. Moreover, the long-term reliability of the mechanical quantity measuring device 1 can be improved.

As described above, in the present embodiment, the semiconductor chip 2 (strain sensor chip) having the strain detection circuit formed thereon is mounted on the base plate 3 which is an insulative structure. Restrictions are less likely to occur, and the usability of the mechanical quantity measuring device is improved. Also, the performance of the mechanical quantity measuring device can be improved.

Although the insulating base plate 3 is used in this embodiment, an insulating ceramic material is preferably used as the material of the insulating base plate 3 . That is, it is preferable to use the base plate 3 made of an insulating ceramic material.

The base plate 3 also has a role of transmitting strain from the object 7 to be measured to the semiconductor chip 2 . become difficult. Therefore, the elastic modulus of the base plate 3 is required to have a value that allows strain to be transmitted between the measurement object 7 and the semiconductor chip 2 . From this point of view, the modulus of elasticity of the base plate 3 is preferably higher than that of the semiconductor chip 2 . A ceramic material is preferable as a material for the base plate 3 because it is an insulating material having a high elastic modulus. As an example, a ceramic material having an elastic modulus of about 310 GPa can be used for the base plate 3 .

As described above, in the present embodiment, solder or metal nanoparticles can be suitably used as the bonding material 5 for bonding the semiconductor chip 2 to the base plate 3 .

When solder is used as the bonding material 5, a high melting point solder having a eutectic point of 275° C. or higher, such as gold-tin solder, can be suitably used. If high-melting-point solder is used as the bonding material 5, it becomes easier to prevent problems caused by melting of the solder used as the bonding material 5 when attaching the mechanical quantity measuring device 1 to the measurement object 7 using solder or the like. . Further, if the bonding material 5 has conductivity, heat generated in the semiconductor chip 2 can be easily conducted to the base plate 3, so that the temperature rise of the semiconductor chip 2 during operation can be easily suppressed.

Gold-tin solder has an elastic modulus of 69 GPa and a yield stress of 275 MPa after solidification, and these values are higher than general semiconductor chip bonding materials such as silver paste. Therefore, gold-tin solder is suitable as the bonding material 5 from the viewpoint that the bonding material 5 has a role of transmitting strain from the base plate 3 to the semiconductor chip 2 .

However, when solder is used as the bonding material 5, in the step of bonding the semiconductor chip 2 to the base plate 3, a process occurs in which the metal solder used as the bonding material 5 solidifies from a molten state. Residual stress resulting from the difference in the amount of thermal deformation between the bonding material 5 and the semiconductor chip 2 generated in this process can cause distortion in the semiconductor chip 2 . It is desirable to suppress the distortion of the semiconductor chip 2 in the process of bonding the semiconductor chip 2 to the base plate 3 as much as possible because it may affect the initial measurement value of the mechanical quantity measuring device 1 .

In addition, in the mechanical quantity measuring device 101 of the above-described example, since the base plate 103 is made of a metal material, the difference in thermal expansion coefficient between the base plate 103 and the semiconductor chip 102 is relatively large. For this reason, in the case of the mechanical quantity measuring device 101 of the above study example, the difference in the amount of thermal deformation between the bonding material 105 and the semiconductor chip 102 generated in the process in which the metal solder used as the bonding material 105 solidifies from the molten state is Since the residual stress becomes considerably large, the strain generated in the semiconductor chip 2 becomes considerably large.

Compared with the mechanical quantity measuring device 101 of the study example using the base plate 103 made of metal, in the case of the mechanical quantity measuring device 1 using the base plate 3 made of an insulating material such as a ceramic material, the base plate 3 and the semiconductor The difference in thermal expansion coefficient with the chip 2 is relatively small. Therefore, compared to the mechanical quantity measuring device 101 of the study example, the mechanical quantity measuring device 1 of the present embodiment uses metal solder even when the semiconductor chip 2 is joined to the base plate 3 by soldering. The difference in the amount of thermal deformation between the bonding material 5 and the semiconductor chip 2 that occurs in the process of solidifying from the molten state is reduced, and distortion that occurs in the semiconductor chip 2 can be suppressed.

However, even if the difference in coefficient of thermal expansion between the base plate 3 and the semiconductor chip 2 can be reduced by using the base plate 3 made of an insulating material such as a ceramic material, solder is not used as the bonding material 5 . When used, it is possible to prevent the semiconductor chip 2 from being distorted due to the residual stress caused by the difference in the amount of thermal deformation between the bonding material 5 and the semiconductor chip 2 generated in the process of solidifying the solder from the molten state. can't

Therefore, in the present embodiment, it is more preferable to use metal nanoparticles as the bonding material 5 for bonding the semiconductor chip 2 to the base plate 3 . Copper nanoparticles are particularly suitable as metal nanoparticles.

Metal nanoparticles (preferably copper nanoparticles) can undergo metal bonding without heating. Suppresses metal bonding. The metal bonding of the metal nanoparticles, which is inhibited by the stabilizer, progresses when the stabilizer is removed from the metal nanoparticles by a method such as heating. It will also bond with metal. Therefore, when metal nanoparticles (preferably copper nanoparticles) are used as the bonding material 5, in the process of bonding the semiconductor chip 2 to the base plate 3, the process in which the bonding material 5 is melted and then solidified is It will not occur.

That is, when solder is used as the bonding material 5, the process of bonding the semiconductor chip 2 to the base plate 3 requires a process of melting the solder once and then solidifying it. Strain is generated in the chip 2. However, when metal nanoparticles (preferably copper nanoparticles) are used as the bonding material 5, in the step of bonding the semiconductor chip 2 to the base plate 3, heating is performed to remove the stabilizer. Metallic bonding of the metal nanoparticles proceeds without melting the material 5 , and the semiconductor chip 2 can be properly bonded to the conductor pattern 4 a on the upper surface of the base plate 3 via the bonding material 5 . Therefore, when metal nanoparticles (preferably copper nanoparticles) are used as the bonding material 5, in the process of bonding the semiconductor chip 2 to the base plate 3, compared to the case of using solder as the bonding material 5, The residual stress generated due to the difference in the amount of thermal deformation between the bonding material 5 and the semiconductor chip 2 is reduced, and the strain generated in the semiconductor chip 2 is reduced. Therefore, when metal nanoparticles (preferably copper nanoparticles) are used as the bonding material 5, distortion generated in the semiconductor chip 2 in the process of bonding the semiconductor chip 2 to the base plate 3 can be suppressed. It is possible to prevent the strain from affecting the initial measurement value of the mechanical quantity measuring device 1 .

As the metal nanoparticles used as the bonding material 5, copper nanoparticles are suitable. Joining becomes possible.

Here, the yield strength required for the bonding material 5 of the mechanical quantity measuring device 1 can be obtained by estimating the stress that can be applied to the bonding material 5 from the strain amount range to be measured by the mechanical quantity measuring device 1. For example, the strain amount range measured by the mechanical quantity measuring device 1 is set to +1000 με, and the stress distribution (B FIG. 6 shows the result of analyzing the stress distribution at the position of -B line). From the graph of FIG. 6, the stress concentrates on the end face (side end face) of the bonding material 5, and a maximum stress of 400 MPa acts. does not occur.

On the other hand, the yield stress of the copper nanoparticles used in the bonding material 5 is estimated using the Hall-Petch formula of Equation 1 below.
_{σy =} σ0+k/√d (Equation 1)

where σ _y is the yield stress of copper nanoparticles, σ ₀ is the yield stress of a single crystal, k is the material constant, and d is the average grain size.

Also, the yield stress σ ₀ is estimated from Equation 2 below when the yield ratio is 0.65.
σ ₀ =σ _s ×0.65 (Equation 2)

where σ _S is the tensile strength and is estimated from Equation 3 below.
σ _S = (2.5 to 3.0) x Hv (Equation 3)

Here, the Vickers hardness Hv of a copper single crystal can be estimated from the following Equation 4 in Non-Patent Document 1 above.
Hv=52+60/√d (Equation 4)

The yield stress σ ₀ in the single crystal is 84.5 to 101.4 MPa (2.5 to 3.0×52×0.65) from Equation 2 above. Further, the material constant k = 60 (Hv·√μm), which indicates the resistance of the slip transfer at the grain boundary in the above Equation 1, is determined from the relationship between the hardness and the stress in the above Equation 2, and the tensile strength σ _S = 2.7 × k × When converted as 0.65 (MPa·√μm), k=60 (Hv·√μm)=105 (MPa·√μm)=3330 (MPa·√nm).

σ _y is σ _y = (84.5 to 101.4) + (3330/√100) = 417.5 to 434.4 MPa from Equation 1 above, where the average particle diameter of copper nanoparticles is Φ100 nm. . In this case, a yield stress of 400 MPa or more, which is required for the bonding material 5, can be secured. If it is desired to measure strain in a wider range with the mechanical quantity measuring device 1, copper nanoparticles with a smaller average particle size may be employed.

As described above, when metal nanoparticles are used as the bonding material 5, the yield strength of the bonding material 5 can be increased by reducing the average grain size of the metal nanoparticles used. 1 can widen the range of the amount of strain that can be measured. Therefore, when copper nanoparticles are used as the bonding material 5, copper nanoparticles having an average particle diameter of Φ100 nm or less can be suitably used.

The semiconductor chip 2 also has a function of detecting (calculating) and outputting a difference (difference) between strain amounts in two directions (X direction and Y direction) perpendicular to each other. Therefore, when thermal deformation occurs in the base plate 3 due to temperature change, if the amount of thermal deformation of the base plate 3 in the X direction and the Y direction is approximately equal, the thermal deformation of the base plate 3 caused by the thermal deformation The strain no longer affects the measurement value of the strain sensing circuit formed on the semiconductor chip 2. FIG. From this point of view, it is preferable that the base plate 3 has a planar shape that is point-symmetrical with respect to the center of the base plate 3 . By doing so, the amount of thermal deformation of the base plate 3 becomes substantially equal in the X direction and the Y direction. can be suppressed or prevented. Therefore, the mechanical quantity measuring device 1 can accurately detect the strain generated in the measurement object 7 while suppressing or preventing the influence of the thermal deformation of the base plate 3 .

Therefore, the base plate 3 preferably has a planar shape that is point-symmetrical with respect to the center of the base plate 3. From this point of view, the planar shape of the base plate 3 may be a square, a circle, or a regular hexagon. , a regular octagonal shape, etc. can be applied. Among these, the square shape (substantially square shape) is most suitable as the planar shape of the base plate 3 . This makes it easier to manufacture the mechanical quantity measuring device 1 and easier to handle the mechanical quantity measuring device 1 .

In the case of FIG. 1, the planar shape of the semiconductor chip 2 is square. An example of the dimensions of the semiconductor chip 2 is, for example, 2.5 mm×2.5 mm×0.13 mm (width×length×thickness). It is 7.5 mm x 7.5 mm x 0.2 mm (width x length x thickness) which is three times. If the base plate 3 is too thick, it will be difficult for strain to be transmitted from the object 7 to be measured to the semiconductor chip 2 . However, if the base plate 3 is too thin, it becomes difficult to manufacture the mechanical quantity measuring device 1 . Therefore, here, the thickness of the base plate 3 is set to, for example, about 0.2 mm.

(Embodiment 2)
FIG. 7 is a plan view (top view) showing the mechanical quantity measuring device 1 according to the second embodiment, and FIG. 8 is a sectional view showing the mechanical quantity measuring device 1 according to the second embodiment. FIG. 1 and FIG. 2 of form 1 above, respectively. A cross-sectional view taken along line A2-A2 in FIG. 7 substantially corresponds to FIG. The mechanical quantity measuring device 1 according to the second embodiment is hereinafter referred to as a mechanical quantity measuring device 1a with a reference numeral 1a.

The main difference between the mechanical quantity measuring device 1a of the second embodiment and the mechanical quantity measuring device 1 of the first embodiment is the base plate 3. As shown in FIG. Here, the base plate 3 of the second embodiment is hereinafter referred to as the base plate 3a by attaching the reference numeral 3a.

The base plate 3a of the second embodiment has basically the same planar shape as the base plate 3 of the first embodiment. However, while the base plate 3 of the first embodiment has a substantially uniform thickness, the base plate 3a of the second embodiment has a relatively uniform thickness of the outer peripheral portion (frame portion 21). thicker than normal.

That is, the base plate 3a of the second embodiment has a frame portion (thick portion, frame portion) 21 on the outer circumference of the base plate 3a. The frame portion 21 is a thickened portion of the base plate 3a, and from another point of view, a portion where the upper surface of the base plate 3a protrudes. Since the frame portion 21 is provided on the outer periphery of the base plate 3a, it can be regarded as the outer peripheral portion of the base plate 3a.

In plan view, the frame portion 21 is provided on the outer periphery of the base plate 3a, and the thickness of the frame portion 21 is thicker than the thickness of the base plate 3a inside the frame portion 21. As shown in FIG. A region of the base plate 3 a inside the frame portion 21 is hereinafter referred to as an inner region 22 . The inner region 22 is surrounded by the frame portion 21 in plan view, and the thickness of the inner region 22 is thinner than the thickness of the frame portion 21 . The height position of the upper surface of the frame portion 21 is higher than the height position of the upper surface of the inner region 22 , and the frame portion 21 protrudes from the upper surface of the inner region 22 . The lower surface of the base plate 3a is formed in the same plane. That is, the lower surface of the frame portion 21 and the lower surface of the inner region 22 are at the same height and form the same plane. The thicker the base plate 3a, the higher the rigidity. Since the frame portion 21 is thicker than the inner region 22 , the rigidity of the frame portion 21 is higher than that of the inner region 22 .

The semiconductor chip 2 is mounted on the inner region 22 of the base plate 3a with the bonding material 5 interposed therebetween. Specifically, the conductor pattern 4a is formed on the upper surface of the inner region 22 of the base plate 3a, and the semiconductor chip 2 is bonded and fixed onto the conductor pattern 4a via the bonding material 5. As shown in FIG. The conductor pattern 4a is preferably formed, but can be omitted if unnecessary.

In the case of FIG. 7, the width of the frame portion 21 is substantially uniform. In this case, the planar shape of the inner region 22 is substantially the same as the planar shape of the base plate 3a (although the planar dimensions are smaller). It becomes square. In the case of FIG. 8, the inner wall (inner side surface, inner peripheral side surface) 33 of the frame portion 21 is substantially perpendicular to the upper surface of the inner region 22 . As another form, the inner wall 33 of the frame portion 21 may be inclined with respect to the upper surface of the inner region 22 .

The rest of the configuration of the mechanical quantity measuring device 1a of the second embodiment is substantially the same as the mechanical quantity measuring device 1 of the first embodiment, so that repeated description thereof will be omitted here.

From the viewpoint of facilitating handling of the mechanical quantity measuring device, it is desirable that the base plate on which the semiconductor chip 2 is mounted has high rigidity. However, in the case of the first embodiment, the thickness of the base plate 3 is uniform. However, since the thickness of the base plate 3 directly under the semiconductor chip 2 is also increased and the rigidity thereof is increased, the strain generated in the object 7 to be measured is less likely to be transmitted to the semiconductor chip 2 via the base plate 3 .

In contrast, in the second embodiment, the base plate 3a has a thick frame portion 21 on the outer periphery, and the semiconductor chip 2 has a thin inner region 22 surrounded by the frame portion 21. installed in the As a result, the presence of the thick frame portion 21 on the outer circumference of the base plate 3a increases the rigidity of the base plate 3a, thereby facilitating the handling of the mechanical quantity measuring device 1a. By mounting the semiconductor chip 2 on the inner region 22 which is thinner than the frame portion 21, the thickness of the base plate 3a directly below the semiconductor chip 2 (corresponding to the thickness of the inner region 22) is reduced and the rigidity is lowered. Therefore, when the mechanical quantity measuring device 1a is attached to the measurement object 7, the thickness of the base plate 3a (corresponding to the thickness of the inner region 22) located between the semiconductor chip 2 and the measurement object 7 is Since the thickness is reduced and the rigidity is lowered, the strain generated in the measurement object 7 is easily transmitted to the semiconductor chip 2 via the base plate 3a. As a result, the sensitivity of the mechanical quantity measuring device 1a can be improved, and the distortion occurring in the measurement object 7 can be accurately detected by the mechanical quantity measuring device 1a.

FIG. 9 shows the thickness of the base plate directly below the strain sensor chip and the thickness of the strain sensor from the object to be measured through the base plate in a mechanical quantity measuring device in which a strain sensor chip (corresponding to semiconductor chip 2) is mounted on the base plate. 7 is a graph showing an example of the results of analysis of strain transmissibility when strain is transmitted to the tip; From FIG. 9, when the thickness of the base plate on which the strain sensor chip is mounted is thicker than 300 μm, the strain transmission rate decreases as the thickness of the base plate increases. It can be seen that even if the thickness of the base plate is made thinner than 300 μm, the strain transmission rate does not increase any further. Therefore, the thickness of the base plate 3a directly under the semiconductor chip 2, that is, the thickness of the inner region 22 is preferably about 300 μm or less. As a result, the strain generated in the object to be measured 7 can be efficiently transmitted to the semiconductor chip 2 via the base plate 3a, so that the strain generated in the object to be measured 7 can be accurately detected by the mechanical quantity measuring device 1a. can do. Considering the productivity and ease of handling of the mechanical quantity measuring device, the thickness of the base plate 3a immediately below the semiconductor chip 2, that is, the thickness of the inner region 22, is preferably about 100 to 300 μm. preferable.

Further, it is more preferable to set the thickness of the frame portion 21 so that the height position of the upper surface of the frame portion 21 is higher than the height position of the highest portion of the wire 6 . As a result, when a sealing portion 31 to be described later is formed, the highest portion of the wire 6 can be reliably covered with the sealing portion 31, so that the wire 6 is prevented from being exposed from the sealing portion 31. easier. For example, when the thickness of the inner region 22 is 100 μm, the thickness of the semiconductor chip 2 is 100 μm, and the height position of the highest portion of the wire 6 is 40 μm higher than the upper surface of the semiconductor chip 2, the frame portion 21 is preferably 240 μm or more, so that the height position of the upper surface of the frame portion 21 is higher than the height position of the highest portion of the wire 6 . Here, the highest portion of the wire 6 corresponds to the highest portion of the wire 6 in the Z direction and refers to the highest portion of the looped wire 6 .

(Embodiment 3)
FIG. 10 is a plan view (top view) showing the mechanical quantity measuring device 1 according to the third embodiment, and FIG. 11 is a sectional view showing the mechanical quantity measuring device 1 according to the third embodiment. A cross-sectional view taken along line A3-A3 in FIG. 10 substantially corresponds to FIG. In FIG. 10, when the sealing portion 31 is seen through, it becomes the same as FIG. The mechanical quantity measuring device 1 according to the third embodiment is hereinafter referred to as a mechanical quantity measuring device 1b with reference numeral 1b.

The mechanical quantity measuring device 1b of the third embodiment differs from the mechanical quantity measuring device 1a of the second embodiment in that a sealing portion (sealing portion) is formed on the base plate 3a so as to cover the semiconductor chip 2. 31 is provided. The sealing portion 31 seals the semiconductor chip 2 and the plurality of wires 6 .

The sealing portion 31 is made of a resin material. The elastic modulus of the sealing portion 31 is preferably lower than the elastic modulus of the semiconductor chip 2 . The elastic modulus of the sealing portion 31 can be, for example, approximately 4 to 14 GPa. The sealing portion 31 is preferably formed on the entire inner region 22 surrounded by the frame portion 21 so as to cover the semiconductor chip 2 . Moreover, it is preferable that the sealing portion 31 fills a space (region, cavity) 32 on the base plate 3a surrounded by the inner wall (inner side surface, inner peripheral side surface) 33 of the frame portion 21 . The planar shape and planar dimensions of the space 32 surrounded by the inner wall 33 of the frame portion 21 match those of the inner region 22 .

Since the outer periphery of the sealing portion 31 is in contact with the inner wall 33 of the frame portion 21 , the planar shape of the sealing portion 31 follows the inner wall 33 of the frame portion 21 and is thus surrounded by the inner wall 33 of the frame portion 21 . The planar shape of the space 32 is the same as that of the space 32 . In the case of FIG. 10, the width of the frame portion 21 is substantially constant regardless of location. In this case, the planar shape of the space 32 surrounded by the inner wall 33 of the frame portion 21 is basically the same as the planar shape of the base plate 3a, and the planar dimension of the space 32 surrounded by the inner wall 33 of the frame portion 21 is is smaller than the plane dimension of the base plate 3a by the width of the frame portion 21. As shown in FIG. Therefore, if the planar shape of the base plate 3a is point-symmetrical with respect to the center of the base plate 3a, the planar shape of the space 32 surrounded by the inner wall 33 of the frame portion 21 and the plane of the sealing portion 31 are the same. The shape can also be a planar shape point-symmetrical with respect to the center of the base plate 3a (and therefore with respect to the center of the sealing portion 31). If the planar shape of the base plate 3a is square, the planar shape of the space 32 surrounded by the inner wall 33 of the frame portion 21 and the planar shape of the sealing portion 31 can also be square.

The mechanical quantity measuring device 1b of the third embodiment is substantially the same as the mechanical quantity measuring device 1a of the second embodiment except that the sealing portion 31 is provided. do.

In the third embodiment, the semiconductor chip 2 and the plurality of wires 6 can be protected by providing the sealing portion 31 . Therefore, the mechanical quantity measuring device 1b can be easily handled, and the reliability of the mechanical quantity measuring device 1b can be improved.

Further, if the sealing portion 31 is thermally deformed due to temperature change, there is concern that stress may be generated in the semiconductor chip. However, since the semiconductor chip 2 has a function of detecting (calculating) and outputting the difference (difference) in the amount of strain in two mutually orthogonal directions (X direction and Y direction), When the sealing portion 31 is thermally deformed, if the amount of thermal deformation of the sealing portion 31 is substantially equal in the X direction and the Y direction, the thermal deformation of the sealing portion 31 is not formed in the semiconductor chip 2. It does not affect the measurement value of the strain sensing circuit. From this point of view, the sealing portion 31 preferably has a planar shape that is point-symmetrical with respect to the center of the sealing portion 31. In the case of FIG. 10, the planar shape of the sealing portion 31 is square. be. As a result, the amount of thermal deformation of the sealing portion 31 becomes substantially equal in the X direction and the Y direction, thereby suppressing or preventing the thermal deformation of the sealing portion 31 from affecting the measurement value of the mechanical quantity measuring device 1b. can do. Therefore, the mechanical quantity measuring device 1b can accurately detect the strain generated in the measurement object 7 while suppressing or preventing the influence of the thermal deformation of the sealing portion 31 .

Further, in the mechanical quantity measuring device 1 of the first embodiment, a sealing resin portion (corresponding to the sealing portion 31) for sealing the semiconductor chip 2 and the wires 6 is formed on the base plate 3. can also

(Embodiment 4)
FIG. 12 is a plan view (top view) showing the mechanical quantity measuring device 1 of the fourth embodiment, and FIG. 13 is a plan perspective view showing the mechanical quantity measuring device 1 of the fourth embodiment. 14 to 16 are sectional views showing the mechanical quantity measuring device 1 according to the fourth embodiment. In FIG. 13, the sealing portion 31 is seen through. 13 substantially corresponds to FIG. 14, and the sectional view at the position of C4-C4 line in FIG. 13 substantially corresponds to FIG. A cross-sectional view at the position of -D4 line substantially corresponds to FIG. The mechanical quantity measuring device 1 according to the fourth embodiment is hereinafter referred to as a mechanical quantity measuring device 1c with reference numeral 1c.

A mechanical quantity measuring device 1c according to the fourth embodiment differs from the mechanical quantity measuring device 1b according to the third embodiment mainly in the base plate 3. As shown in FIG. Here, the base plate 3 of Embodiment 3 is hereinafter referred to as a base plate 3c with reference numeral 3c.

The difference between the base plate 3c of the fourth embodiment and the base plate 3a of the third embodiment is as follows.

In the fourth embodiment, near the corner 41 of the base plate 3c, the inner wall 33 of the frame portion 21 recedes so as to approach the corner 41 (that is, away from the center of the base plate 3c). In other words, the inner wall 33 of the frame portion 21 recedes outward (the side away from the center of the base plate 3c) near the corner 41 of the base plate 3c.

Specifically, the width of the frame portion 21 is substantially uniform except for the vicinity of the corner portion 41 of the base plate 3c, and the inner wall 33 of the frame portion 21 extends along the sides of the base plate 3c. However, in the vicinity of the corner portion 41 of the base plate 3c, the inner wall 33 of the frame portion 21 is retracted (curved) so as to approach the corner portion 41, that is, away from the center of the base plate 3c. In the case of FIGS. 12 and 13, since the planar shape of the base plate 3c is a square, the inner wall 33 of the frame portion 21 is moved near the four corners 41 near the corners 41, that is, the base plate 3c. It is retracted (curved) so as to move away from the center of the plate 3c. By retracting the inner wall 33 of the frame portion 21 so as to approach the corner portion 41, the thin inner region 22 expands so as to approach the corner portion 41 (that is, away from the center of the base plate 3c). . In the case of FIGS. 12 and 13, a region 42 (hereinafter sometimes referred to as a recessed region 42) in which the inner wall 33 of the frame portion 21 is recessed so as to approach the corner 41 is a circular (substantially circular) plane. have a shape. Therefore, in the vicinity of the corner 41 of the base plate 3c, the inner wall 33 of the frame portion 21 has a curved surface without a right-angled corner. Since the receding region 42 is part of the inner region 22, it can be regarded as an expanded region of the inner region 22. As shown in FIG. In the case of FIG. 13, the four corners of the square-shaped inner region 22 are extended outward (sides away from the center of the base plate 3c) to form receding regions 32. In the case of FIG. Further, although the receding region 42 preferably has a circular shape, it may have a shape other than a circular shape, such as a rectangular shape (preferably a rectangular shape or a square shape).

12 and 13, the base plate 3c has sides substantially parallel to the X direction and sides substantially parallel to the Y direction. In this case, the inner wall 33 of the frame portion 21 is retracted to approach the corner portion 41 near the corner portion 41 of the base plate 3c. and the inner wall 33 substantially parallel to the Y direction of the base plate 3c can be prevented from intersecting at right angles near the corners of the base plate 3c.

The outer periphery of the sealing portion 31 is in contact with the inner wall 33 of the frame portion 21 , and the sealing portion 31 has a planar shape along the inner wall 33 of the frame portion 21 . Therefore, the sealing portion 31 is also arranged (filled) in the region 42 where the inner wall 33 of the frame portion 21 is retracted so as to approach the corner portion 41 .

The rest of the configuration of the mechanical quantity measuring device 1c of the fourth embodiment is substantially the same as that of the mechanical quantity measuring device 1b of the third embodiment, so that repeated description thereof will be omitted here.

The sealing portion 31 and the base plate have different coefficients of linear expansion. Therefore, when the temperature changes, stress may occur between the sealing portion 31 and the base plate due to the difference between the shrinkage rate of the sealing portion 31 and the base plate. In the case of the third embodiment (FIGS. 7, 10, and 11), the inner wall 33 of the frame portion 21 substantially parallel to the X direction and the inner wall 33 of the frame portion 21 substantially parallel to the Y direction are connected to the base plate. In the vicinity of the corners of 3a, they intersect at right angles, and the stress generated between the sealing portion 31 and the base plate 3a concentrates there. Therefore, in the case of the third embodiment (FIGS. 7, 10, and 11), when the mechanical quantity measuring device is subjected to repeated temperature changes, the corners of the space 32 surrounded by the inner walls 33 of the frame portion 21 At (from another point of view, the corner of the inner region 22), the sealing portion 31 may peel due to fatigue.

In contrast, in the fourth embodiment (FIGS. 12 to 16), the inner wall 33 of the frame portion 21 is retracted so as to approach the corner 41 near the corner 41 of the base plate 3c. Local concentration of stress generated between the portion 31 and the base plate 3a can be suppressed or alleviated. As a result, peeling of the sealing portion 31 is less likely to occur when the mechanical quantity measuring device is subjected to repeated temperature changes.

Specifically, it is possible to prevent the inner wall 33 of the frame portion 21 substantially parallel to the X direction and the inner wall 33 of the frame portion 21 substantially parallel to the Y direction from crossing each other at right angles near the corners of the base plate 3c. Therefore, local concentration of stress generated between the sealing portion 31 and the base plate 3a can be suppressed or alleviated near the corners of the base plate 3c. Further, since the inner wall 33 of the frame portion 21 is curved near the corner 41 of the base plate 3c, the stress generated between the sealing portion 31 and the base plate 3c near the corner of the base plate 3c is reduced. Local concentration can be suppressed or alleviated. Therefore, when the mechanical quantity measuring device is subjected to repeated temperature changes, peeling of the sealing portion 31 is less likely to occur. Thereby, the long-term reliability of the mechanical quantity measuring device can be improved.

In addition, when the recessed region 42 is provided, peeling of the sealing portion 31 is less likely to occur due to the anchor effect due to the sealing portion 31 being filled in the recessed region 42, compared to the case where the recessed region 42 is not provided. .

In addition, since the mechanical quantity measuring device is used for the purpose of measuring strain, stress may occur between the sealing portion 31 and the base plate due not only to changes in temperature but also to external forces. In the fourth embodiment, even if stress occurs between the sealing portion 31 and the base plate 3c not only due to changes in temperature but also due to external force, local concentration of the stress can be suppressed or alleviated. can be done.

(Embodiment 5)
FIG. 17 is a perspective plan view showing the mechanical quantity measuring device 1 according to the fifth embodiment, and FIGS. 18 and 19 are sectional views showing the mechanical quantity measuring device 1 according to the fifth embodiment. In FIG. 17, the sealing portion 31 is seen through. 17 is the same as FIG. 14, and the cross-sectional view along the C5-C5 line in FIG. 17 substantially corresponds to FIG. A cross-sectional view taken along line D5-D5 substantially corresponds to FIG. The mechanical quantity measuring device 1 according to the fifth embodiment is hereinafter referred to as a mechanical quantity measuring device 1d with reference numeral 1d.

In the fourth embodiment, in order to reduce the rigidity of the base plate 3c in the mounting region of the semiconductor chip 2 and its surroundings, the thickness of the inner region 22 of the base plate 3c is reduced (preferably 300 μm or less), and the base plate The thickness of the frame portion 21 on the outer circumference of the plate 3c is increased. The semiconductor chip 2 mounted on the inner region 22 of the base plate 3 c is covered with the sealing portion 31 . When a stress that pushes out the sealing portion 31 in the thickness direction of the base plate 3c is applied, the sealing portion 31 may peel off from the base plate 3c.

Therefore, in the fifth embodiment, a depression (recess) 51 is provided in the recessed region 42 . The depressed portion 51 is a portion that is locally depressed with respect to the upper surface of the inner region 22 . The recessed portion 51 is recessed in the thickness direction of the base plate 3c. A portion of the sealing portion 31 is intruded into the recessed portion 51 . From another point of view, part of the sealing portion 31 is filled in the recessed portion 51 . As a result, even when a stress that pushes the sealing portion 31 in the thickness direction of the base plate 3c is applied to the sealing portion 31, the anchoring effect (the anchoring effect of the sealing portion 31 filled in the recessed portion 51) It is possible to suppress or prevent the sealing portion 31 from peeling off from the base plate 3c. Therefore, it is possible to further improve the long-term reliability of the mechanical quantity measuring device.

The rest of the configuration of the mechanical quantity measuring device 1d of the fifth embodiment is substantially the same as that of the mechanical quantity measuring device 1c of the above fourth embodiment, so that repeated description thereof will be omitted here.

(Embodiment 6)
FIG. 20 is a plan view (top view) showing the mechanical quantity measuring device 1 according to the sixth embodiment, and FIG. 21 is a sectional view showing the mechanical quantity measuring device 1 according to the sixth embodiment. A cross-sectional view taken along line A6-A6 in FIG. 20 substantially corresponds to FIG. 22 is a perspective plan view showing the mechanical quantity measuring device 1 before the flexible substrate 61 is attached to the base plate 3e, and FIG. 23 shows the mechanical quantity measuring device 1 before the flexible substrate 61 is attached to the base plate 3e. It is a sectional view. In FIG. 22, the sealing portion 31 is seen through. A cross-sectional view taken along line A7-A7 in FIG. 22 substantially corresponds to FIG. The mechanical quantity measuring device 1 of Embodiment 6 is hereinafter referred to as a mechanical quantity measuring device 1e with the reference numeral 1e. Further, the base plate 3 of the sixth embodiment is hereinafter referred to as a base plate 3e by attaching a reference numeral 3e.

In the mechanical quantity measuring device 1e of the sixth embodiment, a flexible substrate 61 is attached (connected) to the base plate 3e in order to extract the electrical signal output from the semiconductor chip 2 to the outside of the mechanical quantity measuring device 1e. ing).

In Embodiment 6, the base plate 3e has a plurality of electrodes 4c as part of the conductor pattern 4 of the base plate 3e. The electrode 4c is electrically connected to a plurality of electrodes 2a of the semiconductor chip 2, and the signal output from the electrode 2a of the semiconductor chip 2 can be output from the electrode 4c of the base plate 3e. The plurality of electrodes 4 c are preferably formed on the upper surface of the frame portion 21 . In the base plate 3e, the electrode 4c formed on the upper surface of the frame portion 21 and the electrode 4b formed on the upper surface of the inner region 22 are electrically formed via wiring 4d inside the base plate 3e. . For example, the base plate 3e can be configured by a laminate of a plurality of insulating layers, and the wiring 4d can be formed by wiring between the insulating layers, wiring in vias provided in the insulating layer (via wiring), and the like. Electrode 2a of semiconductor chip 2 is electrically connected to electrode 4c of base plate 3e via wire 6, electrode 4b of base plate 3e, and wiring 4d.

A plurality of electrodes 4 c of base plate 3 e are electrically connected to a plurality of electrodes 62 of flexible substrate 61 . For example, the plurality of electrodes 4c of the base plate 3e and the plurality of electrodes 62 of the flexible substrate 61 are joined via a conductive joining material 63 such as solder, thereby electrically connecting them. Since the electrode 4c is formed on the upper surface of the frame portion 21, the flexible substrate 61 is joined and fixed to the frame portion 21. As shown in FIG.

Therefore, the electrodes 62 of the flexible substrate 61 are electrically connected to (the electrodes 2a of) the semiconductor chip 2 via the conductive bonding material 63, the electrodes 4c, the wirings 4d and the electrodes 4b of the base plate 3e, and the wires 6. properly connected. Therefore, the base plate 3e has wirings 4d for electrically connecting the electrodes 62 of the flexible substrate 61 to (the electrodes 2a of) the semiconductor chip 2. As shown in FIG.

The rest of the configuration of the mechanical quantity measuring device 1e of the sixth embodiment is substantially the same as that of the mechanical quantity measuring device 1b of the third embodiment, so that repeated description thereof will be omitted here. Here, as the basic structure of the mechanical quantity measuring device 1e, the case where the mechanical quantity measuring device 1b of the third embodiment is applied is illustrated and explained. Any of the mechanical quantity measuring devices 1, 1a, 1b, 1c and 1d of the first to fifth embodiments can be applied. Therefore, the sixth embodiment can be combined with any of the first to fifth embodiments. When the sixth embodiment is combined with the first embodiment, since the base plate 3 does not have the frame portion 21, for example, a plurality of electrodes 4c are provided near the ends of the upper surface of the base plate 3. Then, the plurality of electrodes 4c and the electrodes 62 of the flexible substrate 61 can be bonded via a conductive bonding material 63. As shown in FIG.

In the sixth embodiment, the electrical signal output from the semiconductor chip 2 can be extracted to the outside of the mechanical quantity measuring device 1e via the flexible substrate 61. FIG.

Further, in the sixth embodiment, the flexible substrate 61 is joined and fixed to the frame portion 21, which is thick and has high rigidity, thereby stabilizing the fixing of the flexible substrate 61 to the base plate 3e. can be done. Further, in the case of FIGS. 20 to 23, since the electrodes 4c are provided on the four sides of the frame portion 21, the flexible substrate 61 is joined to the four sides of the frame portion 21 and fixed. Fixation of the flexible substrate 61 to the plate 3e can be stabilized. Thereby, the long-term reliability of the mechanical quantity measuring device 1e can be improved.

Further, since the frame portion 21 is spaced from the semiconductor chip 2 and has high rigidity, the contribution of the frame portion 21 to the transmission of strain from the measurement object 7 to the semiconductor chip 2 is small. The transmission of strain from 7 to semiconductor chip 2 is mostly borne by inner region 22 . In the sixth embodiment, since the flexible substrate 61 is fixed to the frame portion 21 that hardly contributes to the transmission of strain from the measurement object 7 to the semiconductor chip 2, the bonding of the flexible substrate 61 to the frame portion 21 is It is possible to suppress or prevent the measurement value of the mechanical quantity measuring device 1e from being affected.

Unlike the sixth embodiment, the electrodes 2a of the semiconductor chip 2 and the electrodes of the flexible substrate may be directly connected via wires. However, in that case, if the connection relationship is changed or the function of the semiconductor chip 2 is expanded, it cannot be dealt with only by changing the wire connection. it gets complicated. In contrast, in the sixth embodiment, the electrode 62 of the flexible substrate 61 is connected to the electrode 4c of the base plate 3e, and the electrode of the semiconductor chip 2 is connected via the wiring (conductor pattern) and the wire 6 of the base plate 3e. 2a. Therefore, even if the connection relationship is changed or the function of the semiconductor chip 2 is expanded, it can be dealt with by changing the wiring and wire connection of the base plate 3e without changing the flexible substrate 61. Therefore, it is not necessary to change the design of the flexible substrate 61, and the structure of the flexible substrate 61 can be simplified.

Further, unlike the sixth embodiment, when the base plate is conductive, the wires need to be connected directly to the flexible substrate rather than to the base plate. must be connected to the base plate with The properties of the insulating adhesive used to attach the flexible substrate may change due to moisture absorption over a long period of time. is desirable. However, if the sealing resin that covers the connecting portion between the base plate and the flexible substrate is thermally deformed, it may affect the measurement value of the mechanical quantity measuring device. In contrast, in Embodiment 6, the electrode 4c for connecting the flexible substrate 61 is provided on the thick frame portion 21, and the flexible substrate 61 is attached to the frame by using a bonding material such as solder that has high long-term reliability. Since it can be joined to the portion 21, it is not necessary to cover the connecting portion between the flexible substrate 61 and the base plate 3e with resin (sealing resin). Therefore, it is possible to prevent the thermal deformation of the resin covering the connecting portion between the flexible substrate 61 and the base plate 3e from affecting the measured values of the mechanical quantity measuring device.

Although the invention made by the present inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and can be variously modified without departing from the gist of the invention. Needless to say.

For example, instead of the semiconductor chip 2 (strain sensor chip) on which the strain sensing circuit is formed, a strain gauge can be used as the strain detector. can be mounted on

1, 1a, 1b, 1c, 1d, 1e mechanical quantity measuring device 2 semiconductor chip 2a electrodes 3, 3a, 3c, 3d base plates 4, 4a conductor pattern 4b conductor pattern (electrode)
4c electrode 4d wiring 5 bonding material 6 wire 7 measurement object 8 bonding material 11 semiconductor substrates 12a, 12b, 12c, 12d diffusion resistance region 21 frame portion 22 inner region 31 sealing portion 32 space 33 inner wall 41 corner portion 42 receding region 51 Recess 61 flexible substrate 62 electrode 63 bonding material 101 mechanical quantity measuring device 102 semiconductor chip 103 base plate 105 bonding material 107 object to be measured 108 bonding material

Claims (20)

A mechanical quantity measuring device comprising: a strain detector; and an insulating structure on which the strain detector is mounted. In the mechanical quantity measuring device according to claim 1,
The mechanical quantity measuring device, wherein the strain detector is a strain sensor chip or a strain gauge. In the mechanical quantity measuring device according to claim 1,
The mechanical quantity measuring device, wherein the strain detector is mounted on the structure via a conductive first bonding material. In the mechanical quantity measuring device according to claim 3,
The mechanical quantity measuring device, wherein the first bonding material is solder. In the mechanical quantity measuring device according to claim 3,
The mechanical quantity measuring device, wherein the first bonding material is made of metal nanoparticles. In the mechanical quantity measuring device according to claim 5,
The mechanical quantity measuring device, wherein the metal nanoparticles are copper nanoparticles. In the mechanical quantity measuring device according to claim 6,
The mechanical quantity measuring device, wherein the average particle diameter of the copper nanoparticles is Φ100 nm or less. In the mechanical quantity measuring device according to claim 1,
The strain detector outputs a signal corresponding to a difference between a first strain in a first direction and a second strain in a second direction orthogonal to the first direction. In the mechanical quantity measuring device according to claim 1,
The mechanical quantity measuring device, wherein the structure has a planar shape that is point-symmetrical with respect to the center of the structure. In the mechanical quantity measuring device according to claim 1,
The mechanical quantity measuring device, wherein the planar shape of the structure is a square. In the mechanical quantity measuring device according to claim 1,
an outer peripheral portion of the structure has higher rigidity than a first region inside the outer peripheral portion of the structure;
The mechanical quantity measuring device, wherein the strain detector is mounted in the first region. In the mechanical quantity measuring device according to claim 1,
the thickness of the outer peripheral portion of the structure is thicker than the thickness of a first region inside the outer peripheral portion of the structure;
The mechanical quantity measuring device, wherein the strain detector is mounted in the first region. In the mechanical quantity measuring device according to claim 12,
The mechanical quantity measuring device, wherein the structure has a thickness of 300 μm or less immediately below the strain detecting section. In the mechanical quantity measuring device according to claim 12,
A mechanical quantity measuring device, further comprising a sealing resin portion formed on the first region and sealing the strain detecting portion. In the mechanical quantity measuring device according to claim 14,
The mechanical quantity measuring device, wherein the inner wall of the outer peripheral portion of the structure is retracted in the vicinity of the corner of the structure so as to approach the corner. In the mechanical quantity measuring device according to claim 15,
A mechanical quantity measuring device, wherein a region in which the inner wall of the structure is recessed so as to approach the corner has a circular planar shape. In the mechanical quantity measuring device according to claim 16,
A depression is provided in a region where the inner wall of the structure is retracted so as to approach the corner,
A mechanical quantity measuring device, wherein a part of the sealing resin portion is intruded into the recess portion. In the mechanical quantity measuring device according to claim 12,
A mechanical quantity measuring device, further comprising a flexible substrate joined to the outer peripheral portion of the structure. In the mechanical quantity measuring device according to claim 18,
The mechanical quantity measuring device, wherein the structure has wiring for electrically connecting the electrodes of the flexible substrate to the strain detecting section. In the mechanical quantity measuring device according to claim 1,
The mechanical quantity measuring device, wherein the structure is attached to a conductive measurement object using a second conductive bonding material.

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